The present disclosure relates to a power amplifier circuit. Mobile communication terminals such as cellular phones include power amplifier circuits for amplifying radio frequency (RF) signals to be transmitted to a base station. A power amplifier circuit includes a transistor that amplifies an RF signal, and a bias circuit that controls the bias point of the transistor. One known bias circuit of this type is described in, for example, Japanese Unexamined Patent Application Publication No. 2014-171170, which includes an emitter follower transistor that provides a bias signal to the transistor, and a constant voltage generation circuit for generating a constant voltage to be supplied to the collector of the emitter follower transistor.
The bias circuit described in Japanese Unexamined Patent Application Publication No. 2014-171170 may have gain-dispersion characteristics that do not match characteristics required by a customer. Gain dispersion refers to the difference in gains experienced when the power supply voltage to be supplied to a transistor changes, and it is desirable to improve gain-dispersion characteristics to exert the performance of an envelope-tracking power supply circuit.